Improvement of the interfacial integrity of (Ti,Al)N hard coatings deposited on high speed steel cutting tools

With improved microhardness and high temperature resistance, the advanced ( Ti,Al)N hard coating has now been successfully applied to carbide tools for high speed machining, although problems with adhesion at the interface are inevitable when the (Ti,Al)N hard coating is applied to high-speed steel c utting tools. This study investigated a series of multi-layered interfaces consisting of TiAl, TiN and TiAlN in an effort to improve the adhesion stre ngth of (Ti,Al)N deposited on high-speed steel substrates. Deposition of both interlayer and (Ti,Al)N films was conducted sequentially in a single batch process, while cathodic are evaporation was selected as the deposition method for its superior plasma intensity and the flexibility of multiple target arrangement. Microstructure and tribological properties were analyzed by scanning electron microscopy/electron diffraction spectro scopy, particle analyzer, microhardness and wear testers. Results indicated that a combination of TiN and TiAlN interlayers provided an adhesion stren gth of 50 N between (Ti,Al)N and M2 substrate. The tribological performance of (Ti,Al)N thin films on high-speed steel cutting tools was significantly improved. (C) 1999 Published by Elsevier Science S.A. All rights reserved.